This shouldn’t be a big problem.
Even with typical home-printers (reprap/FDM) the back covers most likely will come out usable with enough support material (or some minor changes in design). I’m still using my self-printed cover made on a very cheap printer but I’d like to try it on the original CAD-files as well. +1 for releasing the files!
BTW: I’m curious for what might actually be the reason for not publishing the CAD-data? FP did it with the FP1 - so why not with the FP2 where it would make much more sense due to it’s “openness”.